Job experience with exchange phenomena acquired during two decades is coordinated with the main results of parallel theoretical and laboratory developments. The consciously chosen frame of reference is a general scientific one which it is hoped may even deserve to be termed philosophical. It is this general or philosophical type of thinking which led the French gardener Monier to the invention of reinforced concrete and the French engineer Freyssinet to the development of prestressed concrete. At the present state of development of the science and practice of soil stabilization, qualitative thinking is of paramount importance and premature exclusive emphasis on the quantitative may well stymie the growth of this important discipline.